NIMSAWARD2025-abstracts

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P1-643Reaction Analysis and Anode Development for High-Performance operation of lithium-based Secondary Batteries Reaction Analysis and Anode Development for High-Performance operation of lithium-based Secondary Batteries Li-O2battery, Li evaporated film anode, X-ray absorption analysis:Li-O2battery, Li evaporated film anode, X-ray absorption analysis:•Redox mediators (RM) are effective for high-efficiency operation of Li-O₂ battery cathodes, but they become dysfunctional during recharging. Its mechanism werediligently investigated. •Cycle-life of Li metal were inherently attempted to be extended by controlling the deposition conditions and substrate surface using a vapor deposition method.⚫The dysfunction by accumulation of RM intermediate, Br₃-, is caused by its electrostatic adsorption on HCO₂Li on the Li₂O₂surface.⚫The intrinsic high-density nature of Li bulk improves the cycle-life. Achieving a Li metal anode technology ready for LIB application with an ultra-low pit density.ConclusionConclusion.RM dysfunction in Li-O2batteriesRM dysfunction in Li-O2batteriesHigh-density Li metal anodesHigh-density Li metal anodes⚫Development of a solvent resistant to direct oxidative decomposition at the end of the recharging.⚫Realization of a highly reliable Li metal thin-film anode with a fully inorganic ultrathin solid electrolyte film.⚫Development of Innovative analysis technology during battery operation.Future PlanFuture PlanIntroductionIntroduction•OperandoXAS revealed the accumulation of RM intermediates, which should have a short lifetime during recharging, and ex-situsoft X-ray absorption with special care quantitatively identified the dysfunction factors.•High-density Li contributes to high coulombic efficiency. The control factors to realize a pit-free, conformal thin-film Li anode with a thickness below 1 μm, which is required for future metal anodes in lithium-ion batteries, were found.Theme underDiscussionTheme underDiscussionBattery Materials Analysis Group, GREEN Kimihiko ItoE-mail：： ITO.Kimihiko@nims.go.jpFig. 2.Schematics of the RM dysfunction hypothesis (a), charging characteristics (b), DEMS (c), XAS at the O K-edge and Li K-edge for the charge amount indicated by the arrow in (b) (d), change in XAS at the O K-edge during the final stage of charging (e), and change in formate ion amount quantified by IC (f)..Fig. 1.Schematic diagram of RM operation analysis using operandoXAS and accumulation of detected RM intermediates during charging10 m10 m10 m10 m10 m10 m10 m403 K292 K273 K268 K263 K258 K253 KFig. 3.Schematics of the Li vapor deposition system and temperature dependence of Li film morphology on Cu substrates during the initial deposition stageFig. 4.Changes in Li film density with deposition temperature, changes in coulombic efficiency during repeated 25μm thick Li deposition cycles in Li||Li cells, and the correlation between average coulombic efficiency and Li film density20 m20 mCu substrate surface controlFig. 5.Pit density reduction in ultra-thin Li films (t<1m) via collector foil surface control.